1. Field of the Invention
This invention relates to a closable opening device for a sealed packaging, which includes a flowable medium, wherein the device encompasses a pouring nozzle with a flange, having an internal thread and an external thread, as well as a cylindrical cutting element, which has an upper rim, which defines a planar surface. The lower rim has a tooth or a plurality of teeth, and an internal jacket surface has catches, which act in a radial direction and which interact with catches in a screw cap so that the cutting element pierces the packaging in a screw motion, wherein the pouring nozzle with the flange and the cylindrical cutting element are produced as a one-piece semifinished product.
2. Discussion of Related Art
A closable opening device of the afore-mentioned type is taught by European Patent Reference EP-A-1,088,764. A principle, which is common in closure technology, wherein multi-part closures are produced so that two parts are arranged on top of one another and are injection molded in one piece to be connected to one another via predetermined breaking points. In this connection, the expenditure of tools is reduced because the fitting is simplified, and because the parts connected to one another via predetermined breaking points are arranged in their accurately aligned relative position to one another and must thus only be pushed together. This sufficiently known technology has also been used for the closures, which are of interest, and is also taught by European Patent Reference EP-A-1,084,060, for example. The opening device disclosed differs from the former opening device taught by European Patent Reference EP-A-1,088,764 because the cutting element does not encompass a planar surface at its upper end, but an inclined surface, which bears on a similarly inclined opposite surface in response to the initial actuation of the closing device and which exerts a straight purely transversal force acting at right angles on the packaging to be pierced. This type of motion is in contrast to the type of motion according to European Patent Reference EP-A-1,088,764, which is of interest, where the cutting element is moved through the packaging in a screw motion.
Both documents disclose a semifinished product, which shows a one-piece production of a pouring nozzle including a flange together with a cylindrical cutting element. The cutting element according to European Patent Reference EP-A-1,084,060 does not have a planar surface, neither at the upper nor at the lower rim, which is suitable for being connected to an upper or a lower rim of the pouring nozzle in a revolving manner. A solution is thus disclosed in which the cutting element is produced in an intermediate layer within the pouring nozzle via predetermined breaking points produced as a semifinished product, to be connected to the lower rim of the pouring nozzle via predetermined breaking points.
However, the prefitting, where the cutting element must be inserted into the pouring nozzle, is not as trivial in both of the solutions as it may appear. The mentioned packaging made of laminate, onto which the closing devices, which are of interest herein, are mounted, include at least one plastic film layer, which is difficult to cut through because the material is very tough and must be pierced. This requires for the teeth or for at least the one tooth to be correspondingly sharp and to encompass a sufficient solidity. If the pouring nozzle and the cutting element are simply be pushed together without corresponding specific arrangements by pressure applied from the top and the bottom, the highly delicate teeth would bend, break or would at least become blunt. Consequently, the mode of operation of the opening device is no longer guaranteed. To avoid this, correspondingly complicated fitting devices are used, in which the semifinished products are introduced in an accurately positioned manner and are pushed together only thereafter. Such a fitting is not only correspondingly expensive in terms of equipment, but the fitting speed is relatively slow for a bulk material and causes a large amount of rejects.